This invention relates to an engine control and more particularly an improved engine control system that accommodates and compensates for wear or changes in the condition of the control linkage.
There has been proposed a type of engine control wherein the throttle valve of the engine is maintained in a substantial partially opened condition at idle. The idle speed is maintained by controlling the ignition system or fuel system of the engine to maintain the desired speed which speed would be lower than that at which the engine would run due to the opening of the throttle valve. In this way, throttle response can be improved, particularly at transient conditions when operating in the off idle mode.
Normally many engine controlled Systems, including the one described, utilize a position sensor for sensing the position of the throttle valve as an indication of operator demand in their control strategy. Obviously with an arrangement of the type described, the throttle position sensor is not effective to indicate operator demand during the range of movement when the throttle valve is maintained in a partially opened position and the manual throttle control is moved from its idle position to the position where the lost motion in the connection to the throttle valve is taken up, commonly referred to as the "pick-up position."
Thus, it is necessary to provide an additional sensor which is responsive to the position of the operator controlled element in order to provide the control strategy during at least this range of movement. Of course, the actual throttle position sensor can be dispensed with but this is not necessarily a desirable alternative.
The reason why it is useful to employ the throttle position sensor is that the interconnection between the manual operator and the throttle valve is subject to wear and other factors which can cause the position of the operator control may not be truly indicative of the actual operator demand.
This circumstance is not noticed by the operator because he merely moves the operator controlled element to the position to achieve the engine running condition that he desires. In other words, the operator himself compensates for this wear or change in condition. However, the system has no way of doing this.
It is, therefore, a principal object of this invention to provide an improved control mechanism and strategy for an internal combustion engine of the type wherein the throttle valve is held in a partially opened position at speeds below a predetermined speed and greater than idle speed.
It is a further object of this invention to provide an improved control system and control strategy that automatically compensates for wear or change in condition in the throttle valve actuating system.
In marine applications, there is frequently utilized a type of control that is referred to as a "single lever control". These single lever controls operate through a first range from a neutral position wherein the engine speed may be held relatively constant but the transmission is shifted from either neutral to forward or reverse depending upon the direction of movement of the single lever control. After the shift has been completed, then further movement of the single lever control is effective to open the throttle valve of the engine and increase the speed above the speed which existed at the time the shift was completed. Hence, these systems further add to the linkage and thus may be more subject to wear of other like changes in condition than other controls that employ separate throttle and shift control mechanisms.
It is, therefore, a still further object of this invention to provide an improved control arrangement for an internal combustion engine and transmission system embodying a single lever control.